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When I run on my linux Redhat version 6.8 machine - service iptables status

I get the rules table ( but not if iptables running or not )

Does the following show that iptables is running?

 # service iptables status
 Table: filter
 Chain INPUT (policy ACCEPT)
 num  target     prot opt source               destination
 1    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state   RELATED,ESTABLISHED
 2    ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0
 3    ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0
 4    ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state  NEW tcp dpt:22
 5    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject- with icmp-host-prohibited

 Chain FORWARD (policy ACCEPT)
 num  target     prot opt source               destination
 1    REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject- with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination

Iptables is enabled on boot 

# chkconfig --list iptables
iptables        0:off   1:off   2:on    3:on    4:on    5:on    6:off
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3 Answers 3

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30

There is no such thing as "iptables is running" - there is no dedicated firewall process to monitor.

If the kernel modules are loaded and rules defined (both of which are proven by showing a valid rules table), the filtering is active. It is done in-kernel on events (packet rcv/snd) and not on a separate process.

So: Yes, if the rules shown are what you want, then your firewall is up.

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  • 8
    Not always true. Under CentOS7 you have firewalld installed by default, and you can check its status by running systemctl status firewalld. Also, a package called iptables-services can be installed and if started (service name: iptables), you can check if it's running or not.
    – nKn
    Sep 14, 2016 at 16:07
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    @nKn - the question was: how to verify if iptables is running. firewalld does NOT replace iptables, it's just used to configure it. A dead firewalld with active iptables rules mean, that the firewall is UP, not DOWN
    – Eugen Rieck
    Sep 14, 2016 at 16:11
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    Exactly, and I said it can be checked installing the iptables-services packages and checking systemctl status iptables, which will tell you if iptables is running or not.
    – nKn
    Sep 14, 2016 at 16:14
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    And again, again, again: There is no such thing as "iptables is running".
    – Eugen Rieck
    Sep 15, 2016 at 8:07
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    @nKn Thanks bro. firewalld was my issue!
    – user191528
    Feb 28, 2018 at 10:20
1

This way we can know only if its not running

[root@vm1 ~]# service iptables status iptables: Firewall is not running.

if running , it prints rules table as shown to you

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1

On Ubuntu 20.04, I used service iptables status to show the following:

~$ service iptables status
● iptables.service - netfilter persistent configuration
     Loaded: loaded (/etc/alternatives/iptables.service; enabled; vendor preset: enabled)
     Active: inactive (dead)           
       Docs: man:netfilter-persistent(8)

~$ service iptables restart
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to restart 'iptables.service'.
Authenticating as: <user id>
Password:
==== AUTHENTICATION COMPLETE ===

~$ service iptables status
● iptables.service - netfilter persistent configuration
     Loaded: loaded (/etc/alternatives/iptables.service; enabled; vendor preset: enabled)
     Active: active (exited) since Sun 2021-01-31 08:25:23 EST; 11s ago
       Docs: man:netfilter-persistent(8)
    Process: 140486 ExecStart=/usr/sbin/netfilter-persistent start (code=exited, status=0/SUCCESS)
   Main PID: 140486 (code=exited, status=0/SUCCESS)
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